Telenetics Corporation FT100 S, Инструкция по установке и эксплуатации

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T1 Overview
FT 100S C-7
ESF framing allows logic errors to also be detected due to the CRC-6
error check sequence embedded in the F bit. When the receiving equip-
ment obtains error information, it can communicate the information to
the far end of the T1 link over the FDL channel. Two standard protocols
report errors using the FDL: AT&T Publication 54016 and ANSI
T1.403.
The AT&T method requires that the T1 terminating equipment, the CSU
for example, maintain a 24-hour performance error history. This error
history is transmitted to the Central Office over the FDL after an error
history request message is received from the Central Office. In many
CSUs, an alternate set of registers is maintained in the CSU to allow
customer access to the same error information.
The ANSI method requires that the CSU transmit a performance report
message (PRM) each second over the FDL. This PRM is not sent to any
specific remote location, but is broadcast so that any PRM receiving
device on the T1 line can intercept the message. Rather than transmit-
ting an entire 24-hour history, the PRM contains error information
pertaining to only the previous 4 seconds. It is the responsibility of the
PRM receiver to accumulate the information and store it for 24 hours or
the time desired. This method allows performance monitoring points at
different locations along a T1 network so that error localization can be
determined.
Other proprietary methods of collecting and reporting ESF error infor-
mation have been implemented to enhance the remote T1 device main-
tenance capabilities. Besides ESF error information, CSU configuration
and loop testing functions can be performed remotely using the FDL
data channel. Since these added features are nonstandard, equipment
from different manufacturers is not compatible as far as the proprietary
functions are concerned.